Vintage Synth Repair

I have these 2 vintage synths that have been in a non working state 
for a long time. Since discovering the forum here I thought it would 
be worth a shot to drag them out and see if I could get them working.

The Korg Poly6 produces only gurgling sound and only on some keys 
(other keys no sound). None of the the knobs or switches change the 
sound at all. The keys that do sound do so after a delay. The 
keyboard looks to be in good shape, clean on the inside and out. 
there are no obvious broken parts or wires, a quick look at the 
ciruit boards showed no busted solder connections. (im not a tech by 
any stretch, but i can operate a soldering iron)

The Oberheim OB1 powers up but I get no sound at all. The OB1 also 
looks clean (missing screws that hold the bottom and sides)and a 
quick look around shows no obvious broken parts etc.

Any tips for a novice? Any opinions on how desirable these synths 
are? If i cant fix them I may sell them off to some one who can fix 
and use them.

Schel Sullivan